1. Field of the Invention
The present invention relates to speech coding, and more particularly, to speech coding systems that operate at a bit rate of 4 kbits/s.
2. Related Art
Speech coding systems may not operate effectively at low bit rates. When a small bandwidth is available to encode speech, the perceptual quality of encoded speech declines dramatically. Because of the increase use of wireless communication, there is an effort to reduce the bandwidth upon which such wireless communication systems operate.
To efficiently decrease the wireless bandwidth but still retain a toll quality, a speech coding system generally performs a strict waveform matching. Waveform matching as employed in a low bit rate wireless coding system, such as 4 kbits/s, however, may not perceptually or accurately capture the speech information. Therefore, there is a need in the art for a system that provides a speech coding system with a high perceptual quality at a low bit rate.